SEMAPHORE QUEUE PRIORITY ASSIGNMENT FOR REAL-TIME MULTIPROCESSOR SYNCHRONIZATION

Prior work on real-time scheduling with global shared resources in mul tiprocessor systems assigns as much blocking as possible to the lowest -priority tasks. In this paper, we show that better schedulability can be achieved if global blocking is distributed according to the blocki ng tolerance of tasks rather than their execution priorities. We descr ibe an algorithm that assigns global semaphore queue priorities accord ing to blocking tolerance, and we present simulation results demonstra ting the advantages of this approach with rate monotonic scheduling. O ur simulations also show that a simple FIFO usually provides better re al-time schedulability with global semaphores than priority queues tha t use task execution priorities.